Field
The embodiments described below relate to the processing of angiographic X-ray images acquired while contrast medium is present within a patient volume.
Description
According to conventional angiographic X-ray imaging, a contrast medium is used to enhance the contrast of blood-carrying structures within patient anatomy. For example, a contrast agent is introduced into a patient volume (e.g., via intravenous injection) and an X-ray image of the volume is acquired while the medium is located within the volume. In the X-ray image, structures which contain the agent appear darker than they would otherwise appear.
According to DSA (Digital Subtraction Angiography), a “mask image” of the patient volume is subtracted from an X-ray image acquired as described above. The mask image is acquired without the presence of the contrast medium and represents background anatomic detail. The resulting image is intended to portray only the vessel and perfuse tissue components of the patient volume which include contrast medium.
Two-dimensional (2D) DSA images show a series of images from a particular projection angle. Often, however, it will be advantageous to view this information from several different angles, which may require additional 2D DSAs. However, sometimes patients have difficulty tolerating the contrast medium, either due to allergies or other medical problems (e.g., renal insufficiency). Radiation exposure is a concern and there is a strong desire not to acquire additional X-ray images. In these cases, obtaining additional DSA images is not desirable, even if a different imaging orientation is found that provides a better assessment of the anatomy under scrutiny.
To address the foregoing, a physician either chooses to use existing images or chooses to acquire new images and subject the patient to additional contrast medium injection and X-ray radiation. Known systems therefore involve compromise and use of sub-optimal images or subjection of a patient to additional contrast medium and X-ray radiation.